Hmm not sure would put it first choice, its literally next to the train station, as in trains going past your window if your on that side! so would be pretty noisy. Also feels a bit more isolated from rest of campus. I do know some people who love it there though, so guess its more personal preference.
If Sussex is only your insurance choice you are highly unlikely to get en suite anyway unfortunetly. I was firm and got my 7th choice.